The invention relates generally to packaging systems and deals more particularly with an apparatus for detecting whether a package is filled to a proper level and also deals with a weighing and packaging system which includes the aforesaid apparatus and regulates a package target weight in a stable manner to control the product level in the package.
A variety of types of weighing machines exist today which are capable of weighing out quantities of product within a small tolerance range. However, the composite density of certain types of products may vary significantly, for example, that of cereals or other products which contain a large number of pieces per package which pieces vary in size and shape. Besides the variations in the size and shape of the pieces, the random arrangement of the pieces within a package and degree of settling also affect the composite density and resultant volume of the product.
To please consumers, it is often desirable that packages be filled nearly to the top. However, considering the variations in product density, the package size is often selected such that for a given weight of the product, the average product height is somewhat below the maximum fill height of the package. Settling may occur after a package is initially filled so that it is important that the package be initially filled as high as possible, but nevertheless with the restraint that few or none of the batches of product overflow the package.
It has previously been suggested in U.S. Pat. No. 4,520,883 to discharge each batch of product from a weighing machine into a transparent cylinder prior to discharging it to a package, and to measure the height of the product in the cylinder with photoelectric eyes to estimate the volume of the batch. If the volume is too low, then a target weight for the batch may be increased so that future batches will presumably have a higher volume, and conversely, if the volume is too high, the target weight may be decreased.
One disadvantage of this previous system is that the discharge of the product into the transparent cylinder and the requisite settling time decrease the overall packaging speed. Also, it is possible that the walls of the cylinder may be coated with dust from the product and thereby frustrate the photoelectric eyes. Moreover, the volume of the product in the cylinder may not be the same as the volume of the product in the package because of the differences in how the pieces of the product are arranged in the package compared to the arrangement in the cylinder and the varying degrees of settling.
A general object of the present invention is to provide an apparatus for detecting whether a package is filled to a proper height.
Another general object of the invention is to provide an apparatus of the foregoing type which may be included within a weighing and packaging system without decreasing the packaging rate.
A more specific object of the invention is to provide a system of the foregoing type in which the height of the product in the package when detected approximates the height of the product when the package is obtained by a consumer.
Another specific object of the present invention is to provide a weighing and packaging system including the foregoing apparatus as one component, which system includes means for adjusting a package weight to regulate fill height.
Other objects and advantages of the present invention will become apparent from the following figures and detailed description.